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Fulltext Isolation and characterisation of a Mo-reducing bacterium from Malaysian soil

Chee, H.S., Motharasan Manogaran, Yakasai, M.H., Rahman, M.F.A., Nur Adeela Yasid, Zarizal Suhaili, et al.

Bioremediation Science and Technology Research, 2017;5(2):17-24.
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The issue of heavy metal contamination and toxic xenobiotics has become a rapid global
concern. This has ensured that the bioremediation of these toxicants, which are being carried out
using novel microbes. A bacterium with the ability to reduce molybdenum has been isolated
from contaminated soils and identified as Serratia marcescens strain DR.Y10. The bacterium
reduced molybdenum (sodium molybdate) to molybdenum blue (Mo-blue) optimally at pHs of
between 6.0 and 6.5 and temperatures between 30°C and 37°C. Glucose was the best electron
donor for supporting molybdate reduction followed by sucrose, adonitol, mannose, maltose,
mannitol glycerol, salicin, myo-inositol, sorbitol and trehalose in descending order. Other
requirements include a phosphate concentration of 5 mM and a molybdate concentration of
between 10 and 30 mM. The absorption spectrum of the Mo-blue produced was similar to the
previously isolated Mo-reducing bacterium and closely resembles a reduced phosphomolybdate.
Molybdenum reduction was inhibited by Hg (ii), Ag (i), Cu (ii), and Cr (vi) at 78.9, 69.2, 59.5
and 40.1%, respectively. We also screen for the ability of the bacterium to use various organic
xenobiotics such as phenol, acrylamide, nicotinamide, acetamide, iodoacetamide, propionamide,
acetamide, sodium dodecyl sulfate (SDS) and diesel as electron donor sources for aiding
reduction. The bacterium was also able to grow using amides such as acrylamide, propionamide
and acetamide without molybdenum reduction. The unique ability of the bacterium to detoxify
many toxicants is much in demand, making this bacterium a vital means of bioremediation.
Efflux genes and active efflux activity detection in Malaysian clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA)

Saiful AJ, Mastura M, Zarizal S, Mazurah MI, Shuhaimi M, Ali AM

J Basic Microbiol, 2008 Aug;48(4):245-51.
PMID: 18720500 DOI: 10.1002/jobm.200700387

Efflux-mediated resistance has been recognized as an important contributor of antibiotic resistance in bacteria, especially in methicillin-resistant Staphylococcus aureus (MRSA) isolates. This study was carried out to detect and analyze efflux genes (norA and mdeA) and active efflux activity in a collection of Malaysian MRSA and methicillin-sensitive S. aureus (MSSA) clinical isolates. Nineteen isolates including three ATCC S. aureus reference strains were subjected to PCR detection and DNA sequence analysis for norA and mdeA and active efflux detection using modified minimum inhibitory concentration (MIC) assay. From the 19 isolates, 18 isolates harboured the mdeA gene while 16 isolates contained norA gene. DNA sequence analysis reveals 98-100% correlation between the PCR product and the published DNA sequences in GenBank. In addition, 16 isolates exhibited active efflux activity using the ethidium bromide (EtBr)-reserpine combination MIC assay. To our knowledge, this is the first report on the detection of efflux genes and active efflux activity amongst Malaysian clinical isolates of MRSA/MSSA. Detection of active efflux activity may explain the previous report on efflux-mediated drug resistance profile amongst the local clinical isolates.
Nasal colonisation, antimicrobial susceptibility and genotypic pattern of Staphylococcus aureus among agricultural biotechnology students in Besut, Terengganu, east coast of Malaysia

Zarizal S, Yeo CC, Faizal GM, Chew CH, Zakaria ZA, Jamil Al-Obaidi MM, et al.

Trop Med Int Health, 2018 08;23(8):905-913.
PMID: 29873865 DOI: 10.1111/tmi.13090

BACKGROUND: This study aimed to profile the antimicrobial susceptibility and presence of resistance and virulence genes of methicillin-susceptible Staphylococcus aureus (MSSA) and MRSA nasal carriage, by means of genotypic analyses, in students of a tertiary institution in the state of Terengganu, east coast of Malaysia.
METHODS: A total of 370 agricultural biotechnology students from Universiti Sultan Zainal Abidin in Besut, Terengganu, were enrolled in this study. Antimicrobial susceptibility profiles were evaluated by standard methods. PCR detection of resistance and virulence genes was performed on S. aureus that were methicillin-resistant, macrolide-lincosamide-streptogramin B (MLSB )-positive phenotype and/or positive for the leukocidin (pvl) gene followed by staphylococcal cassette chromosome mec (SCCmec), staphylococcal protein A (spa) and accessory gene regulator (agr) typing.
RESULTS: One hundred and nineteen of 370 students carried S. aureus (32%); 18 of the isolates were MRSA (15%). Erythromycin resistance was detected in 20% (24/119) of which 15% (18/119) were MRSA and 5% (6/119) MSSA. Among the 24 erythromycin-resistant isolates, D-test was positive in 29% (7/24) displaying inducible MLSB , whereas the remaining 71% (17/24) showed constitutive MLSB phenotypes. Nine (7.6%) of 119 isolates were pvl positive: 44% MRSA (4/9) and 56% MSSA (5/9). Staphylococcal surface protein sasX gene was present in 92% of MRSA and 8% of MSSA isolates. The majority of MRSA isolates were agr type I (15/18; 83%). Five spa types identified with spa t037 were predominant, followed by spa types (t304 and t8696) as newly reported Malaysian MRSA in a community setting.
CONCLUSION: The presence of MRSA with SCCmec of hospital-associated features and globally recognised spa types in community setting is worrisome. Furthermore, the presence of MLSB strains among multidrug-resistant (MDR) S. aureus with sasX as well as pvl-positive isolates highlights the potential risk of a community setting in facilitating the dissemination of both virulence and resistance determinants.

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